Income Taxes - Components of Income Tax Provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Current:
Federal	$ (6,631)	$ 431	$ (26)
State and foreign	10,544	704	9,288
Total	3,913	1,135	9,262
Deferred:
Federal	(1,561)	(4,264)	9,498
State and foreign	(3,984)	5,535	(371)
Total	(5,545)	1,271	9,127
Total income tax (benefit) expense	$ (1,632)	$ 2,406	18,389
Charge resulting from remeasured deferred tax asset			2,100
Charge resulting from recording valuation allowance not likely to be utilized			$ 2,600